Different susceptibility to the IL-3 induced-protective effects between Strongyloides ratti and Nippostrongylus brasiliensis in C57BL/6 mice.

Repetitive administration of recombinant IL-3 induced protection against Strongyloides ratti but not against Nippostrongylus brasiliensis in C57BL/6 mice. Numbers of S. ratti were negligible from day 4 to day 6 post-infection in mice injected with IL-3, whereas N. brasiliensis burdens were almost equal from day 4 to day 6 between mice injected with IL-3 or with medium. Mice treated with IL-3 and then concurrently infected with S. ratti and N. brasiliensis were protected from intestinal S. ratti but not from N. brasiliensis. The numbers of intestinal mucosal mast cells were increased by the repetitive IL-3 treatment on one day after the final injection and was augmented by subsequent infection with both nematodes.